This invention relates to a latching mechanism and more particularly to a latch assembly especially suited for securing a vehicle tiltable cab in an upright operating position.
Cab-over-engine vehicles have been manufactured in quantity for at least half a century. An advantage of such vehicles, is that the overall length of a vehicle is reduced as compared to a so-called xe2x80x9cconventionalxe2x80x9d cab behind engine vehicle. For over the highway hauling, cab over engine vehicles are advantageous where the vehicle is operated in jurisdictions where there are legal limits on the overall length of a vehicle. Such vehicles are also advantageous where maneuverability is important such as for intra-city deliveries.
At least in heavy duty vehicles, cab over engine vehicles are of the tilt cab type. That is, the cab is hingedly connected to a vehicle frame near the front of the vehicle, while the back of the cab is releasably latched to the frame.
Cab latches must be durable to withstand long vehicle life. They also must positively maintain a connection between the cab and the frame during vehicle operation. While such latches must maintain positive connections, prior latches which are satisfactory for the purpose, have had inherent drawbacks. If a latch mechanism fails to maintain a connection between the back of a cab and the frame during a collision, severe damage to the cab and a potential excessive injury to occupants can result. As a consequence, prior latches have been designed to maintain cab to frame connections even during severe collisions. While such positive connections are clearly more desirable than a latching mechanism which fails during a collision, a rigidly positioned cab will often experience excessive damage during a collision.
Accordingly, it would be desirable to provide a latching mechanism which is durable, which will maintain a cab to frame connection upon a collision, but yet is energy absorbing to minimize structural damage to the vehicle and injury to a vehicle occupant.
A cab latching mechanism made in accordance with the present invention, positively connects a cab to a frame in a reliable and durable manner. At the same time, the mechanism is designed to partially fail in a controlled manner while maintaining a cab to frame connection in the event of a collision. The partial failure absorbs impact energy minimizing damage to the vehicle. Tests have shown that while the unit partially fails and absorbs energy, it nonetheless meets and exceeds impact test requirements by maintaining a connection between the cab and the vehicle frame upon impact.
In the disclosed and preferred embodiment, a latch subassembly is fixed to a vehicle frame. This subassembly is known as a striker bracket. A coacting subassembly known as a hat section is connected to a cab. The hat section includes a catch which is retained by the latch during normal operation. The latch is of a conventional design which permits ready decoupling when a vehicle cab is to be tilted forwardly such as a for access to the vehicle engine for service.
The hat section includes main and frangible mounting brackets. The main mounting bracket includes a U-shaped tongue which in the preferred embodiment extends downwardly from a body of the main bracket that is secured to the cab. The tongue includes a U-shaped part so that the tongue includes an upstanding portion.
A channel is connected to and extends from the frangible bracket. An upper end of the tongue upstanding part is fixed, as by welding, to the channel. The catch is also fixed to the channel.
In the event of a collision of substantial force, the frangible bracket fails allowing the tongue to extend and increase its effective length as forces are absorbed. This allows the cab to tilt forwardly a relatively small amount as compared to the forward tilting to, for example, gain engine access. The tongue after extension is still connected to both the channel and the body of the main bracket so that the cab, while forwardly tilted a controlled amount, nonetheless is securely fastened to the frame by the latching assembly.
Accordingly, the objects of this invention are to provide a novel and improved energy absorbing latching system for a vehicle of the tilt cab type and a process of absorbing energy in the event of vehicle collisions.